1919] 



YOUNG SEED DISINFECTION 155 



Alcohol was the next disinfectant tried. The same method 

 as the foregoing was employed. The seeds were washed once 

 to prevent further injurious action. No table of results is 

 here included, as I was unable to free any seed from bacteria 

 and still obtain fair germination. The same kinds of seeds 

 as were used in table n were employed in this experiment. 

 Weak alcoholic solutions (10-25 per cent) were used for long 

 periods of time and stronger (25-70 per cent) for short peri- 

 ods as the seed would allow. In only a few cases were sterile 

 seed obtained. Alcohol cannot be entirely discarded as a dis- 

 infectant, as it is very effective in a subsidiary way, as when 

 seeds are first immersed in strong alcohol and then followed 

 by another disinfectant. It serves to remove air cavities which 

 would not otherwise allow proper contact for the disinfectant. 



The next disinfectant used was mercuric chloride. This 

 has also been used very extensively for seed treatment. It is 

 effective in dilute solutions, and for this reason it is neces- 

 sary to remove practically all the solution from the seed, as 

 its antiseptic action prevents the germination and growth of 

 the seed. Some seeds are very easily injured by dilutions that 

 will not kill certain fungi or bacteria. This is especially true 

 with barley. It is also effectively used as the chief disinfectant 

 when preceded by hydrogen peroxide or alcohol. The method 

 used was the same as given with the previous disinfectants. 

 The seeds were washed thoroughly of the HgCl2, as its anti- 

 septic action was found to be injurious in most cases. I was 

 able to disinfect many seeds with mercuric chloride that could 

 not be freed from contamination by any other disinfectant. 

 Table in shows the results with this disinfectant. 



It might be stated again that the seeds used in this table 

 could not in every case be made free from contamination, but 

 when good viable seed were used, a high percentage of the 

 trials proved successful. Many hundred plantlets were ob- 

 tained from seed disinfected by the above methods. From 

 the data at hand it appears that a previous treatment with a 

 good bactericide, such as alcohol or hydrogen peroxide, is to 

 be desired. There are many seeds that will withstand a suf- 



